USB: musb cppi bugfixes

These compilation errors are related to incorrect
debugging macro and variable names and generated the
following errors:

  drivers/usb/musb/cppi_dma.c:437:5: warning: "MUSB_DEBUG" is not defined
  drivers/usb/musb/cppi_dma.c: In function 'cppi_next_rx_segment':
  drivers/usb/musb/cppi_dma.c:884: error: 'debug' undeclared (first use in this function)

Signed-off-by: Hugo Villeneuve <hugo@hugovil.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>